Technical Field
The present invention relates to a DC motor control device for controlling a DC motor and a game machine including such a DC motor control device.
Related Art
In a game machine such as a slot machine or a pinball machine, there are various ways to appeal to a visual sense, auditory sense, or a sensation of a player in order to enhance the interest of the player. In particular, in order to appeal to the visual sense of the player, the game machine may include a movable body, for example, a movable accessory member. A moving range and a moving speed of such a movable body are previously set depending on the performance. Therefore, generally, the movable body is driven by a stepping motor which has an already determined rotation amount per one step, and can control the rotation amount. Then, a processor unit for performance (simply referred to as performance CPU hereafter) which is an example of a host control device, transmits a command to a control circuit of the stepping motor, to rotate the stepping motor by the number of steps corresponding to a moving amount by which the movable body is moved to a specified position in accordance with a gaming state, thereby rotating the stepping motor by the number of steps, and as a result, the movable body is moved to the specified position (for example, see Patent literature 1).
Further, in recent years, the number of movable bodies mounted on the game machine tends to increase in order to enhance the interest of the player. As the number of movable bodies mounted on the game machine increases, the number of motors for driving each movable body also increases. However, the space on the backside of the game machine is limited, and therefore as the number of motors increases, it may be difficult to arrange the motors in the game machine. In particular, since the stepping motor needs to perform excitation control of a plurality of phases, the structure of the stepping motor is complicated, and the size of the stepping motor is correspondingly increased. In addition, the stepping motor is relatively expensive. Therefore, it is undesirable to increase the number of stepping motors.
In addition, in order to enhance the interest of the player, a large movable accessory member may be mounted on the game machine. In order to drive such a movable accessory member, a motor having a high torque is needed. However, in order to increase the torque of the stepping motor, there is no choice but to increase the size of the stepping motor itself, and as a result, it may become more difficult to secure an arrangement space.
On the other hand, there is a DC motor as one type of motor which is generally available. The DC motor is inexpensive compared to the stepping motor and can be smaller than the stepping motor to exert the same torque. Therefore, a technique has been proposed for moving the movable body to a desired movement destination using rotational angle sensors that output detection signals every time the DC motor rotates by a certain rotational angle together with the DC motor (for example, see Patent literature 2).